Marking device, method and apparatus for the production thereof and a method for reading a marking device of this type

ABSTRACT

The invention relates to a marking device ( 21 ) for the identification of objects, comprising a coding consisting of areas ( 24, 25 ) of differing magnetic properties. The marking device is characterised in that it has magnetic areas ( 24, 25 ) consisting of a homogeneous, ferromagnetic or ferrimagnetic material, each of said areas having a magnetic anisotropy with an easy and hard magnetic axis, whereby areas with a different orientation of the easy magnetic axis and/or areas with remanence of different strengths succeed each other in at least one specific direction. The invention also relates to a method for producing a marking device of this type and to apparatus for carrying out the method.

[0001] The invention relates to a marking device for the identificationof objects, with a coding of regions with different magneticcharacteristics, a method and apparatus for making the marking device aswell as a method of reading such a marking device.

[0002] For the marking and thus the individual correlation andverification of check cards, credit cards, access cards, electronic keysor the like, a variety of magnetic codings are used, usually mainly inthe form of a so-called magnetic strip. For the coding, a permanentmagnetic layer is selectively magnetized, i.e. regionally magnetized sothat regions of different magnetization result, whereby in the sense ofthe present description, also nonmagnetized regions, thus regions atwhich the magnetization are zero are included. With correspondingmagnetic field sensors, the magnetic signature or coding can be detectedand processing can then be carried out for the corresponding respectivepurpose.

[0003] There are numerous different proposals for the configuration ofthe magnetic strips. In U.S. Pat. No. 4,650,978, the naturally randomvariations of the magnetic characteristic of a magnetic strip, havingtheir origins in variations in coercivity, granularity, layer thickness,surface profile and especially from random variations in the hysteresisloops and the magnetic histories from which they derive, can be used.The methods of U.S. Pat. Nos. 5,616,904 and 4,837,426 for coding aresimilar. The magnetic structures are digitalized in an appropriate formand used for identification of the objects. A drawback is that themagnetic strips can be manipulated relatively simply and are unstablewith respect to external magnetic fields.

[0004] In U.S. Pat. Nos. 5,480,685 and 5,972,438, magnetic strips aredescribed in which magnetic particles are incorporated in a bindermatrix, whereby the magnetic strips have respectively two layers ofdifferent coercivities. The magnetic strips of U.S. Pat. No. 5,177,344also have magnetic particles within a binder matrix whereby the magneticparticles are so influenced by the application of an external magneticfailed so that they have magnetic regions of different characteristics.This kind of magnetic strips have the drawback that the magneticstructures can be subsequently altered in that the binder can be heatedand the magnetic particles newly oriented by external magnetic fields.

[0005] With the magnetic strips of U.S. Pat. No. 5,365,586, amultiplicity of microcrystalline structures are arranged in a randompattern. The magnetic strips are then subjected to a saturationmagnetization, whereby the remnant noise is read out and used foridentification.

[0006] In U.S. Pat. No. 5,254,843, the random variations in the timesequence of the flux changes in conventional magnetic bands and stripsare used are drawn upon for identification of the respective objects.Here as well, the random structure can easily be reproduced uponrecognition. Aside from this, the method requires a randomness of thevariations with time which is not always produced for certain in machinewriting.

[0007] In the PCT/EP99/08433 which has not been prepublished, a markingdevice is proposed in which the coding has a magnetic base layer and amagnetic coding layer which cooperate so that over the extent of thebase layer and coding layer, there are regions with nonparallel orantiparallel magnetic coupling. Use is here made of the effect ofmagnetic intermediate layer coupling. The marking device has theadvantage of a highly characteristic property which deviates from theusual magnetic marking upon the application of external magnetic fieldswhich is especially that, while the saturation magnetic field blanks outthe nonparallel or antiparallel coupling, the original magnetization isrestored, however, after removal of the external magnetic field. Thecoding can thus not be extinguished by external magnetic fields. Inaddition, use can be made of the effect that magnetic coding which hasweakened, for example, because of long storage times or so-called lostmagnetic codings, can be reactivated by application of a saturationmagnetic field.

[0008] The invention has as its object the provision of a marking deviceof the type described at the outset which has a durable coding which isdifficult to manipulate and is insensitive to external effects. Itshould also enable a verification without data connection to an externalcomputer. A further object is to provide a method and apparatus forproducing such a marking device.

[0009] The first part of the above mentioned object is achievedaccording to the invention in that magnetic regions are provided of ahomogeneous ferromagnetic or ferrimagnetic material that hasrespectively magnetic anisotropy with magnetically soft and magneticallyhard axes [easier and harder axes], whereby in at least onepredetermined direction—this is then the intended readoutdirection—regions with different directions of the easy magnetizationaxes and/or regions with remanences of different magnitudes follow oneanother. The basic concept is thus a provision of a spatial distributionof the magnetic anistropy with respective magnetically soft and hardaxes. Such an anisotropy can also be designated as bidirectionalanisotropy. It is insensitive to external influences to the extent thatthe ferromagnetic or ferrimagnetic material has a Curie temperaturewhich is significantly above room temperature, preferably above 150° C.as is the case with the ferromagnetic materials Co or NiFe. Thus whenreference is made to homogeneous materials, it should be understood thatthese include elemental substances as well as alloys or chemicalcompounds of such substances like oxides, to the extent that they, overthe extent of the coding disregarding possible crystallinity—remainuniform and do not form a matrix system or the like.

[0010] Advantageously, the marking device is such that the magneticregions directly bound one another in the predetermined direction. Thisdoes not exclude an arrangement in which the magnetic regions are alsospaced from one another in the preferred direction whereby the regionsbetween the magnetic regions can be formed as nonmagnetizeable.

[0011] With the invention it is advantageous when the magnetic regionshave saturation magnetization which are of equal magnitude.

[0012] By applying to the coding an external magnetic field up to thesaturation range, there is a homogeneous magnetization over the extentof the coding which forms a reference and enables a verification test.It will be selfunderstood that this is not a compulsory requirementsince the saturation magnetization can also vary over the extent of thecoding. When this variation is stored, it can be determined by theverification test, whether a manipulation has occurred or not. Thecoding as such is stored in terms of the distribution of the magneticbias or an anisotropy. The marking device of the invention can beproduced by applying a coding layer of a homogeneous or ferromagnetic orferrimagnetic carrier and then generating regions of magnetic anisotropywith magnetically harder or softer axes which in at least one directionhave regions with different directions of the soft axis and/or regionswith remanences of different magnitudes following one another. This canbe accomplished with the magnetic regions directly bounding one anotherin succession in the preferred direction and/or by having them spacedapart.

[0013] Since the coding layer is of relatively thin configuration, ithas been found to be desirable to make use of vapor depositiontechnology for building up the layer structure, i.e. thermal vapordeposition, sputtering or the like. The coding layer can be providedwith a protective layer, for example, of DLC (Diamond Like Carbon) orSiC, which preferably also is applied by vapor deposition.

[0014] The impression of the magnetic anisotropy can be effected in asimple manner in that the coding layer can be subjected to anonhomogeneous magnetic field during the build up of the layer. Thedistribution of the nonhomogeneity of this magnetic field enables apattern of different magnetic anisotropies to be provided and the codinglayer to be deposited with a uniform layer thickness.

[0015] The magnetic field, for example, can be generated bynonhomogeneously magnetizing a magnetizable carrier or a magnetizableunderlay for the carrier. In the latter case, the carrier is placed onthe underlay and the coding layer is built up on the combination of theunderlay and carrier.

[0016] The marking device can be especially economically fabricated whena carrier foil is drawn from a supply and brought together with acontinuously displaced magnetic foil and both are fed through a coatingstation in which the coding layer is applied. Then the carrier foil andthe magnetic foil should be again separated. It is advantageous to drawthe magnetic foil also from a supply and then magnetize it anddownstream of the coating station to take it up again in a store. It isespecially advantageous if the magnetic foil is passed in an endlesspath through the coating station. In order to produce such a varyingnonhomogeneity of the magnetic field, the magnetic foils should beindividually magnetized upstream of the coating station and downstreamof the coating station should be again demagnetized or have theirdemagnetization homogenized. Instead of a magnetic foil, the magneticfield can also be created by means of generating coils.

[0017] An apparatus for carrying out the aforedescribed method ischaracterized by

[0018] a) a supply store for a carrier foil;

[0019] b) a coating station for forming the coding layer;

[0020] c) a magnetic field unit juxtaposed at least with the coatingstation for producing a nonhomogeneous magnetic field over the area ofthe carrier foil;

[0021] d) a receiving store for the take up of the marking device;

[0022] e) guide elements and a drive for feeding the carrier foil fromthe supply store through the coating station to the receiving store.

[0023] With this apparatus, it can be provided that the magnetic fieldunit will be arranged upstream of the coating station and that themagnetizable carrier foil is passed through it. Instead, the magneticfield unit can have a magnetic foil which is magnetizednonhomogeneously, whereby the guide elements effect a joining of thecarrier foil and the magnetic foil upstream of the coating station. In aconcrete manner this can be achieved by providing a supply store for themagnetic foil upstream of the coating station and a receiving storedownstream of the coating station and a magnetic field unit which has amagnetizing device which is arranged between the supply store and thecoating station.

[0024] As an alternative thereto, however, the magnetic foil can alsohave an endless configuration and be fed via the guide elements throughthe carrier foil through the coating station. Advantageously, themagnetic field unit should then include a magnetizing unit in the traveldirection of the carrier foil which is upstream of the coating stationand which produces a nonhomogeneous magnetic field, while a quenchingdevice for demagnetization or homogenization of the magnetic field isprovided between the coating station and the magnetizing unit. Themagnetic foil can, for example, be stretched across a support roll whichis juxtaposed with the coating station and over which the carrier foiltravels. Instead, however, the roll periphery itself can be configuredto be magnetizable and here as well a magnetizing unit can be providedfor magnetizing the roll periphery and a quenching unit can be providedfor demagnetizing or homogenizing the magnetic field. The roll peripherycan be provided with a magnetizable coating. In all cases, the quenchingdevice and the magnetizing device should be provided in the direction ofrotation of the support roll one after the other in a region of the rollperiphery which is free from the carrier foil.

[0025] Alternatively, it can be provided that the magnetic field unithave a multiplicity of magnetic field generating coils. These coils canbe arranged in the vicinity of the surface of a carrier roll over theroll periphery of which the carrier foil is guided through the coatingstation so that during the vapor deposition, a nonhomogeneous magneticfield prevails. According to a further feature of the invention, atleast the coating station is provided with a heating unit for producinga homogeneous field preferably above the Curie temperature.

[0026] It is also proposed to provide a further coating station to applya protective layer on the coding layer. In this case, it is desirablefor the coating stations to have vapor deposition units for applicationof the coding layer by means of thermal vapor deposition or sputtering.The supply store or receiving store can advantageously be formed as asupply roll or as a storage roll.

[0027] The method according to the invention can also be so configuredthat the magnetic region has a vapor deposition device which is inclinedto the surface of the carrier whereby with reference to the plane of thecarrier at least two different vapor deposition directions are provided.In this manner alone, the anisotropic distribution according to theinvention can be achieved with different directions of the easymagnetization access. This effect can, however, also be amplified by thesimultaneous impression of a preferably nonhomogeneous magnetic fieldwhich is respectively codirectional with the vapor deposition device.

[0028] More concretely stated, the aforedescribed method can be socarried out that for the vapor deposition in a first vapor depositiondirection region, the carrier is covered with a first mask and that inthe vapor deposition in a second vapor deposition direction at least theregions of the carrier which the first vapor device formed a depositupon are covered with a second mask. Then the first and second vapordeposition units can also be identical when they include units with theaid of which the vapor deposition direction can be altered. It ispossible that in the vapor deposition in the second vapor depositiondirection with the second mask, regions which had not been coveredpreviously be vapor deposition could be covered and at least a portionof these regions, after removal of the second mask and the applicationof a third mask, can be vapor deposited in a third vapor depositiondirection.

[0029] In order to be able to make the marking device in a continuousprocess, the invention provides that a carrier foil and at least twomasking foils are drawn from respective supplies and before each vapordeposition, the carrier foil and one of the masking foils are broughttogether and the vapor deposition carried out from the side of themasking foil and the masking foil again be separated from the carrierbefore the carrier foil is combined with a further masking foil. Themasking foil can be provided with a certain mask pattern already beforeits withdrawal from the supply. Alternatively thereto it is proposedthat the masking foil once withdrawn from the supply but before beingbrought together with the carrier foil, be provided with cutouts. Anapparatus for carrying out the method is characterized by

[0030] a) a supply store for a carrier foil;

[0031] b) a plurality of coating stations for vapor depositing on thecarrier foil in different vapor deposition directions;

[0032] c) a number of supply stores for a masking foil corresponding innumber to the number of coating stations;

[0033] d) receiving stores for taking up the masking foils;

[0034] e) a receiving store for taking up the marking device;

[0035] f) guide elements and a drive for feeding the carrier foil fromthe supply store through the coating stations to a receiving store andfor feeding each of the masking foils together with the carrier foilupstream of a coating station and for separating the carrier foil andthe masking foil downstream of a coating station.

[0036] Advantageously, each coating station has a supply store for amasking foil and a receiving store for the take up of the masking foil.Between each supply store for the masking foil and the junction for themasking foil and the carrier foil, respective mask forming stations canbe provided to produce cutouts in the masking foil and thus impress uponeach masking foil an individual mask pattern. The mask forming stationscan, for example, have a laser burning device which has a control unitfor varying the position of the laser burning device.

[0037] Also with this apparatus, a further coating station can beprovided for applying a protective layer to the coding layer. The supplystore can advantageously be a supply roll and the receiving store astorage roll. Advantageously, the coating station has carrier rolls overwhose roll periphery the carrier foil and the masking foil are guided.

[0038] The method of the invention can also be carried out in suchmanner that initially a layer is applied and this layer during or afterapplication is so magnetized that it has a homogeneous anisotropicdirection so that the layer is then:

[0039] a) subjected to a homogeneous magnetic field and a nonhomogeneoustemperature field, or

[0040] b) subjected to a nonhomogeneous magnetic field and a homogeneoustemperature field, or

[0041] c) subjected to a nonhomogeneous magnetic field and temperaturefield, whereby the temperature lies above the Curie temperature of thelayer.

[0042] By heating the homogeneously magnetized layer to a temperatureabove the Curie temperature of the layer. By heating the homogeneouslymagnetized layer to a temperature above the Curie temperature thedistributions of the different magnetic anistropies can be so controlledthat either the temperature field under simultaneous effect of amagnetic field is nonhomogeneously formed whereby the magnetic field caneither be homogeneous or nonhomogeneously formed or with a homogeneoustemperature field, a nonhomogeneous magnetic field is produced.

[0043] To create the magnetic field both in the formation of the layerand also in the subsequent temperature treatment, a magnetizable carriercan be provided which is correspondingly magnetized. Instead, amagnetizable underlay can also be provided which is correspondinglyhomogeneously or nonhomogeneously magnetized and the carrier with thelayer can be placed on this underlay. To the extent that a magneticfield is impressed subsequent to the layer formation, the combination ofunderlay and carrier can be exposed to the temperature field. To theextent that the method is carried out continuously, a carrier foilshould be drawn from a supply and brought together with a continuouslydisplaced magnetic foil and the two fed through a heating station afterwhich they are again separated. The magnetic foil can also be initiallydrawn from a supply and then magnetized and then downstream of theheating station taken up in a store. Alternatively, the magnetic foilcan be displaced in a closed path through the heating station, wherebythe magnetic foil is magnetized upstream of the heating station anddownstream of the heating station is demagnetized or magnetizationhomogenized. The latter is especially advantageous when the carrier foilis to be exposed to a nonhomogeneous magnetic field. An apparatus forcarrying out your method is characterized in accordance with theinvention by

[0044] a) a supply store for a carrier foil;

[0045] b) a treatment station with a magnetization unit and a heatingunit;

[0046] c) a receiving store for taking up the marking device;

[0047] d) guide elements and a drive for feeding the carrier foil fromthe supply store through the treatment station to the receiving store.

[0048] With the aid of this apparatus a corresponding method can becarried out in which in the treatment station a nonhomogeneous orhomogeneous magnetization and or homogeneous or nonhomogeneous heattreatment can be effected. A prerequisite for the application of ahomogeneous ferromagnetic or ferrimagnetic layer with a homogeneousorientation of the bidirectional anisotropy on the carrier foil.Advantageously this can be achieved with an apparatus in which theaforedescribed apparatus is completed with the following apparatusparts:

[0049] a) a coating station for applying a layer with homogeneousanistropy to the carrier foil;

[0050] b) guide elements and a drive for feeding the carrier foil fromthe supply store through the coating station and the treating station tothe receiving store.

[0051] The coating station is provided with a device for producing asufficiently strong homogeneous magnetic field that fixes the magneticanisotropy. The device can be so configured that directly above thecarrier foil and between the coating station and the carrier foil at alocation at which the material meets the carrier foil a sufficientmagnetic field is created for a new orientation of the magneticanisotropy.

[0052] The application of a magnetic field can be effected in this casealso with the aid of a magnetic foil which is correspondinglyhomogeneous or nonhomogeneous magnetized, whereby the guide elementseffect a joining of the carrier foil and the magnetic foil upstream ofthe treatment station. In more concrete terms, this can be achieved inthat a supply store is provided for the magnetic foil upstream of thetreatment station and a receiving store is provided downstream of thetreatment station and the magnetizing unit is located between the supplystore and the heating device.

[0053] Instead, the magnetic foil can also be of endless configurationand can be fed via the guide elements together with the carrier foilthrough the heating unit. To the extent that a nonhomogeneous magneticfoil is to be produced, the magnetizing unit can be arranged in thetravel direction of the carrier foil upstream of the heating unit and,in addition, a quenching device can be provided for demagnetization orhomogenizing the magnetic field between the heating unit and themagnetizing unit. The magnetic foil can be fed freely over reroutingrollers it can, however, also be stretched over a support roll which isjuxtaposed with the treatment station. In this case, however, anadditional magnetic foil can be eliminated when the roll periphery ismagnetizable or has a magnetizable coating. The quenching device and themagnetization device are preferably located one after the other in thedirection of rotation of the support roll in the region of the supportroll which is free from the carrier foil. Depending upon the type ofmethod, the treatment station can have heating units for locally heatingthe carrier foil whereby lasers are especially suitable for thispurpose. In this case, a homogeneous magnetic field is sufficient asgenerated by a corresponding magnetizing unit. Alternatively, thetreatment station can have a heating device for producing a homogeneoustemperature field as well as a magnetic field for producing anonhomogeneous magnetic field. The alteration of a homogeneouslymagnetized layer in the sense of the present invention can be effectednot only by a subsequent impression with a magnetic field and atemperature field, but local ion bombardment in the sense that thealteration of the direction of the anistropy and/or the remanence willoccur. The ion bombardment can be effected with the aid of a focused ionbeam. Alternatively, the ion bombardment can be effected on an areawidebasis and in the region of the carrier, a nonhomogeneous electroniccharge field can be generated.

[0054] This can be so arranged that an electrically chargeable carrieris charged prior to the ion bombardment with a nonhomogeneous electriccharge. The electric charge can, for example, be produced with the aidof a nonhomogeneously electrically charged underlay on which the carrieris placed.

[0055] The carrier foil is advantageously drawn from a supply and afterthe coating brought together with a continuously displaced charging foilas an underlay. Both are then subjected to areawide ion bombardment.Then they are again separated from one another. The charging foil canalso be drawn from a supply and then charged and after the ionbombardment can be taken up in a store.

[0056] In a variation, the charging foil can be also circulated as anunderlay through the ion bombardment station and the charging foil canbe charged upstream of the ion bombardment station and downstream of theion bombardment station again discharged or can have its electroniccharge homogenized. In this manner individual charge patterns can beapplied.

[0057] Alternatively thereto it is proposed that a charging foil and amasking foil be continuously drawn from respective supplies and broughttogether and that the ion bombardment then be effected from the side ofthe masking foil and the masking foil again separated from the carrierfoil. In this case, the masking foil, after withdrawal from the supplyand prior to being brought together with the carrier foil, should beprovided with cutouts. It can also be provided that the masking foil beheld in a supply already provided with cutouts.

[0058] The apparatus can be formed analogously to the apparatus in whicha treatment station is provided with a magnetization unit and a heatingunit. Instead of this treatment station, now an ion

[0059] The apparatus can be formed analogously to the apparatus in whicha treatment station is provided with a magnetization unit and a heatingunit. Instead of this treatment station, now an ion bombardment stationis provided for the ion beam treatment of the layer on the carrier foil.With the aid of the ion bomb station, a focused ion beam can begenerated whereby a controlled device cooperates therewith is a targetedcontrol of the ion beam. A nonhomogeneous ion beam treatment can,however, be produced with an areawide ion beam when it impinges onregions of the carrier foil with a nonhomogeneous charge field which hasa charge corresponding to the charge of the ions and thus can repel theion beam in these regions so that the ions of the beam do not impingeupon the carrier foil.

[0060] Finally, it can, for example also be effective to guide anelectrically chargeable carrier foil through the ion bombardmentstation, where a charge device applies a nonhomogeneous electric chargethereto. Alternatively, an electrically chargeable charging foil can bepassed through the ion bombardment station and can have been providedwith a nonhomogeneous electric charge, the guide elements effecting ameeting of the carrying foil and the charging foil upstream of the ionbombardment station. A supply store can be provided for the carrier foilupstream of the ion bombardment station and a receiving store downstreamof the ion bombardment station while a charging device for applying anonhomogeneous charge to the charging foil is arranged between thesupply station. Instead, the carrier foil can, however, be configured asan endless charging foil and guided via the guide elements together withthe carrier foil through the ion bombardment station. In this case, thecharging device is provided in the travel direction of the carrier foilupstream of the ion bombardment station and a quenching device can beprovided for discharging or homogenizing the electric charge bottom theion bombardment and the charging device. The charging foil can also bestretched over a support roll which is juxtaposed with the ionbombardment station.

[0061] In the latter case, a charging foil can be eliminated when theroll periphery of the support roll is chargeable with an electriccharge. Then a charging device for charging the roll periphery and aquenched device for discharging or homogenizing the electric charge ofthe roll periphery should be provided.

[0062] To enable the roll periphery to be chargeable, it can also beprovided with a corresponding coating.

[0063] The charging device and the discharging device are advantageousdisposed one after the other in the direction of rotation of the supportroll and in a region of the support roll which is free from the carrierfoil.

[0064] As an alternative thereto, it can be provided that a masking foilis fed through the ion bombardment station and that the guide elementseffect a meeting of the carrier foil and the masking foil upstream ofthe ion bombardment station in such manner that the ion bombardment iscarried out from the side of the masking foil and that the guideelements separate the carrier foil and masking foil downstream of theion bombardment station. In this case as well, the ion bombardment canbe effected on an area wide basis, whereby the impact on the layer onthe carrier foil is limited by the cutouts in the masking foil.

[0065] In the apparatus, an already preformed masking foil can beintroduced. As an alternative thereto, it is proposed in accordance withthe invention that between a supply store for the masking foil and themeeting of the masking foil and the carrier, a mask forming station bearranged to produce the cutouts in the masking foil, whereby the maskingforming station is provided as a laser burning unit with a controldevice for varying the position control of the laser burning unit.

[0066] The subject of the invention is also a method of reading theabove described marking devices with the aid of at least one magneticfield sensor.

[0067] According to the invention, the coding is subjected to at leasttwo reading processes whereby one reading process is effected in a zerofield and one reading processing an externally applied magnetic field orthe reading processes are effected under different magnetic fields. Inthe first mentioned reading process, information stored in the magneticregions is detected based upon location, for example, by reading certainfeatures of the hysteresis loops. In the second reading process, whichpreferably is carried out under saturation magnetization, thedistribution of the saturation magnetization is detected and comparedwith a predetermined reference structure. The sequence of the tworeading processes does not matter.

[0068] It is also of advantage that for the reading of the markingdevices according to the invention, conventional magnetic field sensorsare suitable, that is, for example, inductive sensors, magnetoresistivesensors, magneto-optical sensors, Hall-effect sensors or SQUID sensors.

[0069] The reading which is resolved as to location is effected byrelative movement between the magnetic field sensor and the markingdevice and it is not significant whether one or the other of the two ismoved. A plurality of magnetic sensors can also be used to detect themagnetic structure of the marking device in a stationary state but as afunction of position.

[0070] To detect the information stored in the coating, various featuresof the hysteresis loop can be considered. It is simple to detect theremanence in a zero field or a very small magnetic field. Instead, itis, however, also possible to detect the flux change at the boundariesbetween two positions since with the marking device according to theinvention at these boundaries stray fields arise whose distribution in acertain direction from the coding.

[0071] The invention is described in greater detail with reference tothe drawing based upon examples. The drawing shows:

[0072]FIG. 1 a plan view on a portion of a marking device in remanence,illustrating the hysteresis loops of two magnetic regions;

[0073]FIG. 2 a longitudinal section through the marking device accordingto FIG. 1;

[0074]FIG. 3 a diagram illustrating the principles of the marking deviceaccording to FIGS. 1 and 2 with a magnetic field sensor;

[0075]FIG. 4 an illustration of the principles for producing anonhomogeneous magnetic field by means of a magnetizable underlay;

[0076]FIG. 5 an apparatus for producing a marking device by means oflayer build up in a nonhomogeneous field;

[0077]FIG. 6 an apparatus for producing a marking device by means ofinclined vapor deposition in two deposition directions;

[0078]FIG. 7 a device for producing a marking foil by means of ionbombardment.

[0079] In FIGS. 1 and 2, a marking device 21 has been shown in which ahomogeneous ferromagnetic layer 23 is applied to a carrier 22. Theferromagnetic layer 23, for example, of FE, CO, NI, a magnetic rareearth metal, an alloy or a ferrite itself has a randomly arranged arrayof magnetic regions distributed over its area and, for example,indicated at 24 or 25. In the production of the ferromagnetic layer 23by corresponding local field application a magnetic anisotropy is sogenerated that in the magnetic regions 24, 25 the easy access isoriented corresponding to the arrows (in FIG. 2 symbolized by the pointin the circle).

[0080] If a measurement is carried out by means of a magnetic fieldsensor in the direction indicated by the arrow below the carrier 22(FIG. 2), i.e. the reading direction, the magnetic regions 24 have amagnetic characteristic corresponding to the hysteresis loop 26 whilethe magnetic regions 25 have a magnetic property corresponding to thehysteresis loops 27. At the transitions between two enabling regions 24and 25, there is a difference in the strengths of the remanentmagnetizations with respect to a reading direction. The flux changethere produces stray fields which, like the local magnetization itselfhas a structure affecting the signal pattern which corresponds to thecoding.

[0081] By imposing an external magnetic field in the saturation range,in the directions of the magnetic field H a uniform magnetizationarises. Upon removal of the magnetic field, the illustrated structurereturns.

[0082] In FIG. 3, the marking device 21 has been turned so that thecarrier 22 is disposed at the upper side and the ferromagnetic layer 23on the lower side. Below it, a magnetic field sensor 31 is arrangedwhich has a reading head 32 over which the marking device 21 with thecarrier 22 is displaced past in the pull through direction. At theboundaries of the different magnetized regions in the zero field, astray field is generated which induces a current pulse 33. Via anexternal current source 34 an additional current can be fed to a coil 35at the reading head 32 whereby at the location of the detection anexternal magnetic field is detected. By the readout, a signal developswhich is processes in an amplification stage 37 and in a further stage38. If the external current is equal to zero then the stored informationcan be read. If the current is sufficient to saturate the ferromagneticlayer 23, the current pulse 33 disappears. In this manner a verificationtest of the coding is possible.

[0083] It is especially advantageous for the magnetic field sensor 31and the ferromagnetic layer 23 to match each other in shape so that thesaturation field corresponds to a field stretch in which thecharacteristic lines of the magnetic field sensor 31 are linear toenable a distinction between saturation of the coding and saturation ofthe magnetic field sensor. A further possibility is overcoming thesaturation problem of several magnetic field sensors, for example,inductive or magneto-resistive magnetic field sensors is for thesaturation field to be applied in a direction which does correspond tothe sensitive region of the magnetic field sensor. It is alsoadvantageous to use a magnetic field sensor which is suitable fordetection of the local magnetization of the layer, for example (amagneto-optical detection device) to exclude influence on the externalfield on the sensitivity of the magnetic field sensor.

[0084]FIG. 4 shows a carrier plate 41 on which a magnetic foil 42 isplaced. The magnetic foil 42 is magnetized perpendicularly to the layerplane in strips—for example indicated at 43—and indeed in a strip 43with a preferred direction downwardly and an adjacent strip 43 with apreferred direction upwardly as symbolized by the arrows. This yields astray field configuration as shown schematically by the semicircles 44.The so-configured stray field is sufficient to localize the direction ofthe magnetic anisotropy.

[0085] On the magnetic foil 42 a carrier foil 45 is placed and in which,by means of the magnetic foil 42, a magnetic field distribution isproduced whose components in the layer plane vary in accordance with thepattern therebelow which has been indicated by the horizontal arrows onthe carrier foil 45. By the vapor deposition of a suitable ferromagneticmaterial or ferrimagnetic material on the carrier foil 45, the magneticfield distribution determines the spatial distribution of the magneticanisotropy and thus the signature of the coding.

[0086]FIG. 5 shows an apparatus 46 in which the principle of FIG. 4 isused in a continuous manufacturing process. The apparatus 46 is disposedin a housing not either shown in detail and which is under high vacuum.

[0087] The apparatus 46 has two vapor deposition stations 47 and 48,whereby each vapor deposition station 47, 48 has a support roll 49, 50associated therewith and which are flanked by respective reroutingrollers 51, 52 or 53, 54 in their lower regions.

[0088] The first vapor deposition station 47 is provided above therespective support roll 49 with a vapor deposition device 55. Thesupport roll 49 is provided with a magnetic layer along its rollperiphery, for example, a thin polymer layer of about 3 mm, in which ahigh proportion of ferromagnetic particles are embedded. Below thesupport roll 49 and between the associated rerouting rolls 51, 52, atthe left side a magnetizing unit 59 is provided which can have a row ofpermanent magnets and/or magnetic field generating coils and which iscapable of providing the magnetic layer 58 with a certain magnetizationpattern which in its simplest form can have the form shown in FIG. 4.The magnetic layer 58 produces a nonhomogeneous magnetic fieldcorresponding to its magnetization. To the right adjacent themagnetizing unit 59, a quenching unit 60 is arranged which eithercompletely demagnetizes the magnetic layer 58 or magnetizes ithomogeneously and thus eliminates the nonhomogeneous magnetizationimpressed by the magnetizing unit 59. On a supply roll 61, a carrierfoil 62, for example, a polyester foil, is rolled up. In operation, thecarrier foil 62, by the drive of the support rolls 49, 50, is withdrawnfrom the supply roll 61 and pass around the first rerouting roller 51and onto the magnetic layer 58 where it is entrained by the rotation ofthe support roll 59 therewith. In the vapor deposition unit 55, thecarrier foil 62 is provided with a layer 63 of ferromagnetic material.Through the spatial magnetic field distribution, created by the magneticlayer 58, the desired directional distribution of the magneticanisotropy is produced.

[0089] After passing around the rerouting rollers 52, 53, the carrierfoil 62 passes through the second vapor deposition station 48 where ittravels onto the periphery of the respective support roll 50 and travelswith the support roll 50. It thus passes the vapor deposition device 64which applies a protective layer 65 over the entire area, for example,of DLC. After traversing the second vapor deposition station 28, thecarrier foil passes around the last rerouting roller 54 and is taken upby a storage roll 66. It can then be subsequently subdivided intoindividual sheets.

[0090] With the apparatus 71 according to FIG. 6, another manufacturingprocess is used. The apparatus 71 has three vapor deposition stations72, 73, 74, whereby the vapor deposition stations 72, 73, 74 havesupport rolls 75, 76, 77 associated with them and which, in their lowerregions, are flanked by rerouting rollers 78, 79 or 80, 81 or 82, 83.Above the support rolls 75, 76, 77, respective vapor deposition devices84, 85, 86 are arranged.

[0091] Upstream of the first support roll 75 there is located a supplyroll 88 on which a carrier foil 89 is rolled. Above the supply roll 88,a further supply roll 90 is provided on which a making foil 91 isprovided.

[0092] The further supply roll 90 is juxtaposed with a roll 92 with theaid of which opens, for example, indicated at 93 can be burned into themasking foil 91.

[0093] Upstream of the second support roll 76 there is found a thirdsupply roll 94 on which a second masking foil 95 is rolled. The thirdsupply roll 94 is also here juxtaposed with a laser device 96 withopenings, for example, designated with 97 are burned out of the maskingfoil 95.

[0094] In operation, the carrier foil 89 and the masking foils 91, 95are drawn at the same speed from their supply rolls 88 or 90 or 94, forexample by the drive of the support rolls 75, 76, 77. In the maskingfoils 91, 95 shortly downstream of their respective supply rolls 90 or94, a pattern of cutouts 93, 99 is burned with the aid of the laserdevices 92, 96. By corresponding control of the laser beams generated bythe laser devices 92, 96, more can also be provided—, predeterminedpatterns or continuously changing random patterns, for example, madewith the aid of a random generator, can be produced, which are in acomplimentary relationship as further detailed below.

[0095] The carrier foil 89 and the masking foil 91 travel onto the firstrerouting roller 78 together and are entrained by the support roll 75.

[0096] The masking foil 91 lies outside of the carrier foil 89. Both arebased together in the upper region of the support roll 75 past the firstvapor deposition device 84 whereby the vapor deposition device vapordeposits a ferromagnetic layer 98 in a first direction with the deposithowever appearing only in the regions of the cutouts 93 on the carrierfoil 89. After passing around the rerouting roller 79, the masking foil91 is led upwardly away from the carrier foil 89 and rolled up on astorage roll 99.

[0097] The carrier foil 89 then travels horizontally to the nextrerouting roller 80 and combines their with the second masking foil 95.Both then travel on the support roll 76. With the aid of the vapordeposition unit 85, a second ferromagnetic layer 100 is vapor depositedon the carrier foil 89 with a second direction different from the first.This deposition on the carrier foil 89 is also delimited to the regionsof the cutouts 97. The cutouts 97 are so arranged that they leave on thecarrier foil 89 only regions free which are covered in the first coatingstation by the masking foil 91 there. Because of the different vapordeposition directions of the vapor deposition devices 84 and 85, regionsare produced with different directions of the easy axis of magneticanistropy.

[0098] Next, the thus coated carrier foil 89 loops around the reroutingrollers 81, 82 and passes into the last support roll 77. With the aid ofthe further deposition unit 86, a protective layer 103 is applies to theferromagnetic coding layer 102. After passing the last rerouting roller83 the carrier provider 89 with the coating is rolled up on a storageroll 103. It can then be correspondingly packaged depending upon itsrespective use.

[0099]FIG. 7 shows a further apparatus 111 for the production of amarking device with regional anisotropy. It has, in the sequence oftravel, a first vapor deposition station 112, an ion bombardment 113 anda second vapor deposition station 114. The stations 112, 113, 114 areassociated with support rolls 115, 116, 117 which are flanked in theirlower regions respectively by two rerouting 118, 119 or 120, 121 or 122,123.

[0100] The vapor deposition stations 112, 114 are each provided with avapor deposition device 124, 125 above the associated support roll 115,117. In the ion bombardment station 113, above the associated supportroll 116 an ion bombardment device 117 is arranged. Below the supportroll 116 and between the rerouting rollers 120, 121 associated therewithis a charging distribution device 128 deposited at the left side andwith which the support roll 116 is provided with regions with positivecharge and/or regions of negative charge. This can be effected, forexample, in accordance with the principles of the laser printer. Forthis purpose, the support roll 116 is provided with an electricallychargeable coating 129. To the right of the charge distributing device128, a quenching device 130 is arranged which either completelydischarges the surface of the support roll 116 or provides it with ahomogeneous electric charge.

[0101] On a supply roll 131, a carrier foil 132 is rolled. In operation,the carrier foil 132, for example by driving the support rolls 115, 116,117, is drawn from the supply roll 131, passes around the firstrerouting roller 118 and passes onto the periphery of the first supportroll 115 with which it is entrained. The carrier foil is therebydisplaced past the first vapor deposition device 124 and is provided, bysputtering under a homogeneous magnetized field, with a ferromagneticlayer 133. With this layer 133, the carrier foil travels around the nextfollowing rerouting rollers 119, 120 and onto the periphery of thesecond support roll 116 and loops about the latter. Thus the carrierfoil travels past the ion bombardment device 127 which fires onto thelayer 133 over the entire width of the carrier foil 132. Because of thecharge distribution on the surface of the support roll 116, which wasproduced previously by the charge drawbacks device 128, there are formedon the surface of the first layer 133, regions which are repellant forthe ions of the ion bombardment device 127 and regions with attractivepotential. In the regions with attractive potential, the layer 133 is soinfluenced that the magnetic anisotropy is altered in its direction sothat a coding layer 134 results.

[0102] The support roll 116, on each pass has its charge homogenized bythe quenching device 130, that is either completely discharged orprovided with a homogeneous charge, at each pass upstream of the chargedistribution device 128 so that the charge distribution device 128always produces a new randomly generated distribution charge pattern onthe support roll 116.

[0103] After looping around the rerouting rollers 121, 122, the carrierfoil 132 travels into the second vapor deposition station 114 where itshere guided again over the periphery of a support roll 117. There thelayer 133 receives, with the aid of the vapor deposition device 125 andover its entire area, a protective layer 135.

[0104] The carrier foil 132 then travels around the last reroutingroller 123 and is rolled up in a storage roll 136. It can besubsequently subdivided.

[0105] It will be understood that in FIGS. 6 and 7 as well devices 71,111 can be disposed within a housing which is under high vacuum.

1. A marking device 21 for the identification of objects, with a codingof regions (24, 25) with different magnetic properties, characterized inthat magnetic regions (24, 25) of a homogeneous ferromagnetic materialor ferrimagnetic material are provided which each have a magneticanisotropy with magnetic easy and hard axes, whereby in at least acertain direction, regions with different orientations of the easy axisand/or regions with remanences of different amplitude follow oneanother.
 2. A marking device according to claim 1, characterized in thatmagnetic regions (24, 25) in the determined direction are directlyadjacent one another.
 3. A marking device according to claims 1 or 2,characterized in that magnetic regions (24, 25) in the determineddirection are spaced apart.
 4. A marking device according to claim 3,characterized in that magnetic regions between the magnetic regions aremagnetizable.
 5. A marking device according to one of claims 1 to 4,characterized in that magnetic regions have saturation magnetizations ofequal magnitudes.
 6. A method of producing a marking device according toone of claims 1 to 5, characterized in that a coding layer (23) of ahomogeneous ferromagnetic material or ferrimagnetic material is appliedto a carrier (22) and that regions (24, 25) with magnetic anistropy withmagnetically easier and harder axes are so produced that at least in acertain direction regions with different orientations of the easier axisand/or regions with reminances of the different amplitudes follow oneanother.
 7. The method according to claim 6, characterized in that thecoding layer (23) is so constructed that magnetic regions (24.25)directly border one another in the certain direction.
 8. The methodaccording to one of claims 6 or 7, characterized in that the codinglayer is so constructed that the magnetic regions are spaced apart inthe certain direction.
 9. The method according to claim 8, characterizedin that the coding layer is so constructed that the regions between themagnetic regions are not magnetizable.
 10. The method according to oneof claims 6 to 9, characterized in that the coding layer (23) is soconstructed that the magnetic regions (24, 25) have saturationmagnetizations of equal magnitudes.
 11. The method according to one ofclaims 6 to 10, characterized in that the coding layer (23) is producedby vapor deposition.
 12. The method according to one of claims 6 to 11,characterized in that a protective layer (65, 101, 135) is applied tothe coding layer (63, 64, 100, 134), especially by vapor deposition. 13.The method according to one of claims 6 to 12, characterized in that thecoding layer (63) upon layer build up is impressed with a nonhomogeneousmagnetic field.
 14. The method according to claim 13, characterized inthat to produce the magnetic field a magnetizable carrier isnonhomogeneously magnetized.
 15. The method according to claim 13,characterized in that to form the magnetic field a magnetizable underlay(58) is nonhomogeneously magnetized and that the carrier (62) is placedon this underlay (58) and the build up of the coding layer (63) iseffected on the combination of the underlay (58) and the carrier (62).16. The method according to claim 15, characterized in that a carrierfoil is drawn from a supply and brought together with a continuouslydisplaced magnetic foil and both are fed through a coating station inwhich the coding layer is applied.
 17. The method according to claim 16,characterized in that the carrier foil and magnetic foil are separateddownstream of the coating station.
 18. The method according to claim 16or 17, characterized in that the magnetic foil is drawn from a supplyand the magnetized and that downstream of the coating station is takenup in a store.
 19. The method according to claim 16 or 17, characterizedin that the magnetic foil (58) is spaced endlessly through the coatingstation.
 20. The method according to claim 19, characterized in that themagnetic foil (58) is magnetized upstream of the coating station (47)and downstream of the coating station (47) is demagnetized or has itsmagnetization homogenized.
 21. The method according to claim 13,characterized in that the magnetic field is produced by magnetic fieldgenerating coils.
 22. The apparatus for carrying out the methodaccording to one of claims 13 to 21, characterized by a) a supply store(61) for a carrier foil (62); b) a coating station (47) for depositing acoding layer (63); c) a magnetic field unit (59) juxtaposed with atleast the coating station (47) for producing a nonhomogeneous magneticfield over the area of the carrier foil (62); d) a receiving store (66)for taking up the marking device; e) guide elements (49 to 54) and adrive for feeding the carrier foil (62) from the supply store (61)through the coating station (47) to the receiving store (66).
 23. Theapparatus according to claim 22, characterized in that the magneticfield unit is arranged upstream of the coating station and that amagnetizable carrier foil is fed through them.
 24. The apparatusaccording to claim 22, characterized in that the magnetic fieldarrangement has a magnetic foil which is nonhomogeneous magnetized andthat the guide elements effect a meeting of the carrier foil and themagnetic foil upstream of the coating station.
 25. The apparatusaccording to claim 24, characterized in that a supply for the magneticfoil is provided upstream of the coating station and that the magneticfield unit has a magnetization device which is disposed between thesupply store and the coating station.
 26. The apparatus according toclaim 24, characterized in that the magnetic field is formed with anendless configuration and is passed by the guide elements together withthe carrier foil through the coating station.
 27. The apparatusaccording to claim 26, characterized in that the magnetic field unit hasa magnetizing device located in the travel direction of the carrier foilupstream of the coating station and generates a nonhomogeneous magneticfield, and that a quenching device for demagnetization or homogenizingthe magnetic field between the coating station and the magnetizingdevice.
 28. The apparatus according to claim 26 or 27, characterized inthat the magnetic foil is stretched over a support roll which isassociated with the coating station.
 29. The apparatus according toclaim 22, characterized in that the coating station (47) is associatedwith a support roll (49) over the roll periphery (58) of which thecarrier foil is passed through the coating station (47) and that theroll periphery (58) is configured to be magnetizable.
 30. The apparatusaccording to claim 29, characterized in that the magnetic field devicehas a magnetizing unit (59) for magnetizing the roll periphery (58)which generates a nonhomogeneous magnetic field and that a quenchingdevice (60) is provided for demagnetization or homogenizing the magneticfield.
 31. The apparatus according to one of claims 28 or 30characterized in that the roll periphery has a magnetizable coating(58).
 32. The apparatus according to one of claims 29 or 31,characterized in that the quenching device (60) and the magnetizing unit(59) are disposed in the direction of rotation of the support roll (57)one after the other in the region of the support roll (47) which is freefrom the carrier foil (62).
 33. The apparatus according to claim 22,characterized in that the magnetic field unit has a plurality ofmagnetic field generating coils.
 34. The apparatus according to claim33, characterized in that the coils are arranged in the region of thesurface of a carrier roll over whose roll periphery the carrier foil isfed through the coating station.
 35. The apparatus according to one ofclaims 22 to 34, characterized in that at least the coating station hasa heating device for generating a homogeneous temperature field.
 36. Theapparatus according to one of claims 22 to 35, characterized in that afurther coating station (48) is provided for applying a protectivecoating (65) to the coding layer.
 37. The apparatus according to one ofclaims 22 to 36, characterized in that the coating stations (47, 48)have at least one vapor deposition unit.
 38. The apparatus according toone of claims 22 to 37, characterized in that the supply store or thesupply stores and the receiving store or the receiving stores areconfigured as supply rolls (61) or storage rolls (66).
 39. The apparatusaccording to one of claims 22 to 38, characterized in that the coatingstations (47, 48) have at least one carrier roll (49, 50) over whoseroll peripheries the carrier foil (62) is fed.
 40. The method accordingto one of claims 6 to 12, characterized in that the regions have layersformed by inclined vapor deposition on the surface of the carrier (89),whereby at least two different vapor deposition directions are used. 41.The method according to claim 40, characterized in that the vapordeposition directions are effected by identically oriented magneticfields.
 42. The method according to one of claims 40 and 41,characterized in that the vapor deposition in a first vapor depositiondirection regions of the carrier (89) are covered by a first mask andthat during the vapor deposition in a second vapor deposition directionat least the regions of the carrier (89) which were vapor deposited withthe first vapor deposition direction are covered with a second mask(95).
 43. The method according to claim 42, characterized in that in thevapor deposition in the second vapor deposition direction, regions havenot theretofore been vapor deposited are also covered by the second maskand at least a portion of these regions, after removal of the secondmask and application of a third mask are vapor deposited in a thirdvapor deposition direction.
 44. The method according to claim 42,characterized in that a carrier foil (89) and at least two masking foils(91) and (95) are drawn from respective supplies (88, 90, 94) and beforeeach vapor deposition, the carrier foil (89) and one of the maskingfoils (91, 95) are brought together and the vapor deposition is theneffected from the side of the masking foil (91, 95) and the masking foil(91) is again separated from the carrier foil (89) before the carrierfoil (89) is brought together with a further masking foil together. 45.The method according to claim 44, characterized in that the maskingfoils (91, 95) are each provided with cutouts (93, 97) after beingwithdrawn from the supply (90, 94) and before being brought togetherwith the carrier foil (89).
 46. The apparatus for carrying out themethod according to one of claims 40 to 45, characterized by: a) asupply store 88 for a carrier foil (89); b) a plurality of coatingstations (72, 73) for vapor depositing the carrier foil (89) indifferent vapor deposition directions; c) a number of supply stores (90,94) have masking foils (90, 95) corresponding in number to the number ofcoating stations (72, 73); d) receiving stores for taking up the maskingfoils; e) a receiving store (104) for taking up the marking device; f)guide elements (75 to 83) and a drive for feeding the carrier foil (89)from the supply store (78) through the coating stations (72, 73) to thereceiving store (104) and for feeding together the carrier foil (89)with each of the masking foils (91, 95) upstream of a coating station(72, 73) and for separating the carrier foil (89) and the masking foil(91, 95) downstream of a coating station.
 47. The apparatus according toclaim 46, characterized in that each coating station (72, 73) isassociated with a supply store (90, 94) for a masking foil (91, 95) anda receiving store (99, 101) for taking up the masking foil (91, 95). 48.The apparatus according to one of claims 46 or 47, characterized in thatbetween supply stores (90, 94) for the masking foil (91, 95) and themeeting of the masking foils (91, 95) and the carrier foil (89),respective mask forming stations (92, 96) are arranged for producingcutouts (93, 97) in the masking foils (91, 95).
 49. The apparatusaccording to claim 48, characterized in that the mask forming stations(92, 96) has a laser burning unit.
 50. The apparatus according to claim49, characterized in that the mask forming stations (92, 96) each have acontrol device for varying the position of the laser burning unit. 51.The apparatus according to one of claims 46 to 50, characterized in thata further coating station (74) is provided for providing a protectivelayer (103) on the coding layer (102).
 52. The apparatus according toone of claims 46 to 51, characterized in that the supply stores areconfigured as supply rolls (88, 90, 94) and the receiving stores asstorage rolls (99, 101, 104).
 53. The apparatus according to one ofclaims 46 to 52, characterized in that the coating stations (72, 73, 74)have carrier rolls (75, 76, 77) under whose roll peripheries the carrierfoil (89) and the masking foils (91, 95) are guided.
 54. The methodaccording to claims 6 to 12, characterized in that at least onehomogenized magnetized layer is created and the layer is subjected to:a) a homogeneous magnetic field and a nonhomogeneous temperature field;or b) a nonhomogeneous magnetic field and a homogeneous temperaturefield; or c) a nonhomogeneous magnetic field and a temperature field,whereby the temperature lies above the Curie temperature of the layer.55. The method according to claim 54, characterized in that to createthe magnetic field, magnetizable carrier is magnetized.
 56. The methodaccording to claim 54, characterized in that to create the magneticfield, magnetizable underlay is magnetized and that the carrier with thelayer is placed on this underlay and the combination of the underlay andcarrier is subjected to the temperature field.
 57. The method accordingto claim 56, characterized in that a carrier foil is withdrawn from asupply and brought together with a continuously displaced magnetic foilas an underlay and both are fed through a heating station.
 58. Themethod according to claim 57, characterized in that a carrier foil andmagnetic foil are separated downstream of the heating station.
 59. Themethod according to one of claims 57 and 58, characterized in that themagnetic foil is drawn from a supply and then magnetized and downstreamof the heating station is taken up in a store.
 60. The method accordingto one of claims 57 and 58, characterized in that the magnetic foil isshaped in an endless path through the heating station.
 61. The methodaccording to claim 60, characterized in that the magnetic foil ismagnetized upstream of the heating station and demagnetized downstreamof the heating station or has its magnetization homogenized.
 62. Theapparatus for carrying out the method according to one of the claims 54to 61, characterized by: a) a supply store for a carrier foil; b) atreatment station with a magnetizing unit and a heating unit; c) areceiving store for taking up the marking device; d) guide elements anda drive for feeding the carrier foil from the supply store through thetreatment station to the receiving store.
 63. The apparatus according to62, characterized by: a) a coating station for applying a homogenizinglymagnetized coating to the carrier foil; b) guide elements and a drivefor feeding the carrier foil from a supply store through the coatingstation and the treating station to the receiving store.
 64. Theapparatus according to one of claims 62 to 63, characterized in that themagnetizing unit has a magnetic foil which is magnetized and that theguide elements effect a meeting of the carrier foil and the magneticfoil upstream of the treating station.
 65. The apparatus according toclaim 64, characterized in that a supply store for the magnetic foil isprovided upstream of treatment station and a receiving store is provideddownstream of the treating station, and that the magnetizing unit isdisposed between the supply store and the heating unit.
 66. Theapparatus according to claim 64, characterized in that the magnetic foilhas an endless configuration and is passed by the guide elements throughthe heating unit together with the carrier foil.
 67. The apparatusaccording to claim 66, characterized in that the magnetizing unit isdisposed in the travel direction of the carrier foil upstream of theheating unit and produces a nonhomogeneous magnetic field and that aquenching device is provided between the heating unit and themagnetizing unit for demagnetization or homogenizing the magnetic field.68. The apparatus according to claims 66 or 67, characterized in thatthe magnetic foil for stretch over a support roll which is associatedwith the treating station.
 69. The apparatus according to claim 62,characterized in that the treating station is associated with a supportroll over whose roll periphery the carrier foil is advanced based thetreating station and that the roll periphery is of a magnetizableconfiguration.
 70. The apparatus according to claim 69, characterized inthat the magnetization unit produces a nonhomogeneous magnetic field andthat a quenching device for demagnetization or homogenization of themagnetic field.
 71. The apparatus according to claims (69, 70),characterized in that the roll periphery has a magnetizable coating. 72.The apparatus according to claims 70 or 71, characterized in that thequenching unit and the magnetization unit follow one another in thedirection of rotation of the support roll in the region of the supportroll which is free from the carrier foil.
 73. The apparatus according toone of claims 62 to 72, characterized in that the treating station hasheating devices for local heating.
 74. The apparatus according to claim73, characterized in that the heating device or devices have at leastone laser.
 75. The apparatus according to one of claims 73 to 74,characterized in that the treating station has a magnetizing device forproducing a homogenized magnetic field.
 76. The apparatus according toclaim 75, characterized in that the treating station has a heating unitfor producing a homogeneous temperature field as well as a magnetizingunit for producing a nonhomogeneous magnetic field.
 77. The apparatusaccording to one of claims 62 to 76, characterized in that a furthercoating station is provided for applying a protective layer to thesecond layer.
 78. The apparatus according to one of claims 62 to 77,characterized in that the coating station has one or more vapordeposition units.
 79. The apparatus according to one of claims 62 to 77,characterized in that the supply store is formed as a supply roll andthe receiving store as a storage roll.
 80. The apparatus of claims 63 to79, characterized in that the coating station and the treating stationhave carrier rolls over whose roll peripheries the carrier foil is fed.81. The method defined in one of claims 6 to 12, characterized in thatat least one homogeneous magnetized layer (133) is formed and the layer(133) is locally so subjected to an ion bombardment that it is locallycaused to have a variation in its easy axis and/or its remanence. 82.The method according to claim 81 characterized in that the ionbombardment is effected with the aid of a focused ion beam.
 83. Themethod according to claim 81, characterized in that the ion bombardmentis effected on an areawide basis and in the region of the carrier (132)a nonhomogeneous electric charge field is produced.
 84. The methodaccording to one of claims 81 to 83, characterized in that anelectrically chargeable carrier is charged electrically nonhomogeneouslyprior to the ion bombardment.
 85. The method according to claim 83,characterized in that an electrically chargeable underlay (129) isnonhomogeneous electrically charged and that the carrier (132) placed onthis underlay (129) and the ion bombardment is effected on thecombination of the underlay (129) and the carrier (132).
 86. The methodaccording to claim 85, characterized in that a carrier foil is drawnfrom a supply and after a coating is brought together with acontinuously improved charging foil (129) and both are subjected to ionbombardment.
 87. The method according to claim 86, characterized in thatthe carrier foil and charging foil are separated after the ionbombardment.
 88. The method according to one of claims 86 or 87,characterized in that the charging foil is drawn from a supply and thencharged and after the ion bombardment is taken up in a store.
 89. Themethod according to one of claims 86 or 87, characterized in that acharging foil (129) is circulated as an underlay through an ionbombardment station (113) and the charging foil (129) upstream of theion bombardment station (113) is charged and downstream of the ionbombardment (113) is discharged or has its electric homogenized.
 90. Themethod according to one of claims 81 or 82, characterized in that acarrier foil and masking foil are continuously drawn from respectivesupply and brought together and that the ion bombardment is theneffected from the side of the masking foil and the masking foil is thenseparated from the carrier foil.
 91. The method according to claim 90,characterized in that the masking foil after being withdrawn from thesupply and before being brought together with the carrier foil isprovided with cutouts.
 92. The apparatus for carrying out the methodaccording to one of claims 81 to 91, characterized by: a) a supply store(131) for a carrier foil (132); b) an ion bombardment station (113) forthe bombardment of the layer (133); c) a receiving store (136) for themarking device; d) guide elements (115) through (123) and a drive fordisplacing the carrier foil (132) from the supply store (131) throughthe ion bombardment station (113) to the receiving store (136).
 93. Thedevice according to claim 92, characterized by: a) a coating station(112) for applying a homogeneous magnetized layer (133) to the carrierfoil (132); b) guide elements (115) through (123) and a drive forfeeding the carrier foil (132) from the supply store (131) through thecoating station (112) and the ion bombardment station (113) to thereceiving store.
 94. The apparatus according to one of claims 92, 93,characterized in that the ion bombardment station has a focused ion beamand a control device is provided for the targeted control of the ionbeam.
 95. The apparatus according to one of claims 92, 93, characterizedin that an electrically chargeable carrier foil is passed through theion bombardment station and is provided with a nonhomogeneous electriccharge by a charging unit.
 96. The apparatus according to one of claims92, 93, characterized in that the ion bombardment station has anelectrically chargeable charging foil passed through which is providedwith a nonhomogeneous electric charge and that the guide elements effecta meeting of the carrier foil and charging foil upstream of the ionbombardment station.
 97. The apparatus according to claim 96,characterized in that a supply store is provided for the charging foilupstream of the ion bombardment station and a receiving store isprovided downstream of the ion bombardment station and a charging unitis provided for the nonhomogeneous charging of the charging foil betweenthe supply store and the ion bombardment station.
 98. The apparatusaccording to claim 96, characterized in that the charging foil has anendless configuration and is based via the guide elements together withthe carrier foil through the ion bombardment station and that thecharging device in the travel direction of the carrier foil is providedupstream of the ion bombardment station and a quenching device isprovided between the ion bombardment station and the charging device fordischarging or homogenizing the electric charge.
 99. The apparatusaccording to claim 98, characterized in that the charging foil forstretching over a support roll which is associated with the ionbombardment station.
 100. The apparatus according to one of claims 92,93, characterized in that the ion bombardment station (113) isassociated with a support roll (116) over the roll periphery (129) ofwhich the carrier foil (132) is passed through the ion bombardmentstation (113) and that the roll periphery (129) is chargeable with anelectric charge whereby a charging unit (128) is provided for chargingthe roll periphery (129) and a quenching device (130) is provided fordischarging or homogenizing the electric charge of the roll periphery(129).
 101. The apparatus according to claim 100, characterized in thatthe roll periphery has a coating chargeable with an electric charge.102. The apparatus according to one of claims 98 to 101, characterizedin that the discharging unit 130 and the charging unit (128) areprovided one after the other in the rotation direction of the supportroll (116) in a region of the support roll (116) which is free from thecarrier roll (132).
 103. The apparatus according to one of claims 92,93, characterized in that the ion bombardment station has a masking foilbased therethrough and that the guide elements effect a meeting of thecarrier foil and masking foil upstream of the ion bombardment station insuch manner that the ion bombardment is effected from the side of themasking foil and that the guide elements separate the carrier foil andmasking foil downstream of the ion bombardment.
 104. The apparatusaccording to claim 103, characterized in that between a supply store forthe masking foil and the meeting of the masking foil and carrier foil amask forming station is proposed for producing cutouts in the maskingfoil.
 105. The apparatus according to claim 104, characterized in thatthe mask forming station has a laser burning device.
 106. The apparatusaccording to claim 104, characterized in that the mask forming stationhas a control device for varying the position of the laser burningdevice.
 107. The apparatus according to one of claims 92 to 106,characterized in that a further coating station (114) is provided forapplying a protective layer 135 on the layer
 133. 108. The apparatusaccording to one of claims 93 to 107, characterized in that the coatingstations (112, 114) have at least one vapor deposition unit (124, 125).109. The apparatus according to one of claims 92 to 108, characterizedin that the supply store is configured as a supply roll and thereceiving store as a storage roll.
 110. The apparatus according to oneof claims 93 to 109, characterized in that the coating station and theion bombardment station have carrier rolls over the roll peripheries ofwhich the carrier foil is fed.
 111. A method of reading a marking deviceaccording to one of claims 1 to 5 with the aid of a magnetic fieldsensor, characterized in that the coding is subjected to at least tworeading processes whereby one reading process is effected in a zerofield and a reading process is effected in an external magnetic field orthe reading processes are effected in different external magnetic field.112. The method according to claim 111, characterized in that onereading process is carried out with saturation magnetization.
 113. Themethod for reading marking devices according to one of claims 1 to 5with the aid of magnetic field sensor characterized in that at least onereading process is carried out in the remanence.
 114. The method forreading marking devices according to one of claims 1 to 5 with the aidof magnetic field sensor characterized in that at least one readingprocess is carried out in the flux change at the boundary between twomagnetic regions is detected.
 115. The method for reading markingdevices according to one of claims 1 to 5 with the aid of magnetic fieldsensor characterized in that at least two reading processes are carriedout without an external magnetic field and that the coding before areading process is magnetized in one direction and before a furtherreading process is magnetized in another direction up to saturation.